Binyamin Netanyahu warned about them in a preelection televised Likud advertisement, and on Wednesday the first-of-its-kind seminar focusing on the threat posed by shoulder-held anti-aircraft missiles to civil aviation was held at the Foreign Ministry in Jerusalem. According to official estimations, tens of thousands of shoulder-to-air missiles are currently in the hands of terror groups - mostly in unstable countries like Afghanistan and Iraq. The threat, an officer from Air Force Intelligence told the seminar on Wednesday, was "real" and could materialize in any place at any time. "MANPADS [Man Portable Air Defense Systems] are a reliable and cheap weapon that is easy to use," the officer told the group, which included arms experts from Turkey, China, the United States and the United Nations. Shoulder missile attacks, the officer said, were also very difficult to foresee since all they required were people and the missile launcher. "They don't leave an intelligence signature," the officer said. Israel - which already faced this threat when two missiles narrowly missed an Arkia airliner carrying 261 passengers in Kenya in 2002 - viewed shoulder missiles as a real and immediate danger, said Foreign Ministry Director-General Ron Prosor. The relatively low cost of this weapon system compared to the high cost of protecting civilian aircrafts made this type of weapon a potential threat to peace and security. "This is a common threat for a number of countries," Prosor told reporters. "The missiles are cheap but the potential damage is great." According to Christophe Carle from the United Nations Institute for Disarmament Research, the world has so far been lucky. "The ease of using the weapons and the difficulty of protecting airports and aircraft are very tempting for terror groups," he said. Last year, Carle said, the UN passed a resolution acknowledging the threat, which it equated with the threat posed to the world by weapons of mass destruction. To stop the proliferation of shoulder missiles, he said, countries needed "good housekeeping" and to make sure that arms manufacturers don't transfer the missiles to guerrilla and terror groups. The IAF Intelligence officer told the group that, while there had been some 25 attempts to shoot down aircraft with shoulder missiles since 1973, the reason the number had stayed relatively low was because terror groups were so far reluctant to engage in such large-scale attacks. "Not every terror group is ready to launch such an attack," the officer said.